The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A010693 Periodic sequence: Repeat 2,3. 24
 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3, 2, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 COMMENTS a(n) = smallest prime divisor of n!! for n >= 2. For biggest prime divisor of n!! see A139421. - Artur Jasinski, Apr 21 2008 Let A be the Hessenberg matrix of order n, defined by: A[1,j]=1, A[i,i]:=-3, A[i,i-1]=-1, and A[i,j]=0 otherwise. Then, for n>=1, a(n)=-charpoly(A,-2). - Milan Janjic, Jan 27 2010 Simple continued fraction of 1+sqrt(5/3) = A176020. - R. J. Mathar, Mar 08 2012 p(n) = a(n-1) is the Abelian complexity function of the Thue-Morse word A010060. - Nathan Fox, Mar 12 2013 LINKS INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 466 G. Richomme, K. Saari, L. Q. Zamboni, Abelian complexity in minimal subshifts, J. London Math. Soc. 83(1) (2011) 79-95. G. Richomme, K. Saari, L. Q. Zamboni, Abelian complexity in minimal subshifts, arXiv:0911.2914 [math.CO], 2009. Index entries for linear recurrences with constant coefficients, signature (0,1). FORMULA a(n) = 5/2 - ((-1)^n)/2. a(n) = 2 + (n mod 2) = A007395(n) + A000035(n). - Reinhard Zumkeller, Mar 23 2005 a(n) = A020639(A016767(n)) for n>0. - Reinhard Zumkeller, Jan 29 2009 From Jaume Oliver Lafont, Mar 20 2009: (Start) G.f.:(2+3*x)/(1-x^2). Linear recurrence: a(0)=2, a(1)=3, a(n)=a(n-2) for n>=2. (End) a(n) = A001615(2n)/A001615(n) for n > 0. - Enrique Pérez Herrero, Jun 06 2012 a(n) = floor((n+1)*5/2) - floor((n)*5/2). - Hailey R. Olafson, Jul 23 2014 a(n) = 3 - ((n+1) mod 2). - Wesley Ivan Hurt, Jul 24 2014 MAPLE A010693:=n->2+(n mod 2): seq(A010693(n), n=0..100); # Wesley Ivan Hurt, Jul 24 2014 MATHEMATICA Table[5/2 - (-1)^n/2, {n, 0, 100}] or a = {}; Do[b = First[First[FactorInteger[n!! ]]]; AppendTo[a, b], {n, 2, 1000}]; a (* Artur Jasinski, Apr 21 2008 *) 2 + Mod[Range[0, 100], 2] (* Wesley Ivan Hurt, Jul 24 2014 *) PadRight[{}, 120, {2, 3}] (* Harvey P. Dale, Jan 20 2023 *) PROG (Haskell) a010693 = (+ 2) . (`mod` 2) -- Reinhard Zumkeller, Nov 27 2012 a010693_list = cycle [2, 3] -- Reinhard Zumkeller, Mar 29 2012 (Magma) [2 + (n mod 2) : n in [0..100]]; // Wesley Ivan Hurt, Jul 24 2014 (PARI) a(n)=3 - (n+1)%2 \\ Charles R Greathouse IV, May 09 2016 CROSSREFS Cf. A139421. Cf. A026549 (partial products). Sequence in context: A339092 A165587 A356464 * A158478 A139713 A171465 Adjacent sequences: A010690 A010691 A010692 * A010694 A010695 A010696 KEYWORD nonn,easy AUTHOR EXTENSIONS Definition rewritten by Bruno Berselli, Sep 30 2011 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified February 8 20:00 EST 2023. Contains 360152 sequences. (Running on oeis4.)